Process for manufacturing a detergent briquette



United States Patent 3,240,712 PROtIESS FGR MANUFACTURING A DETERGENT ERIQUETTE Albert Lyle Sehulerud, Nutiey, Amory Earl Austin, EL, Colonia, and Kenneth Harold Speclthals, Jersey City, NJ, assignors to Colgate-Palmolive Company, New York, N.Y., a corporation of Delaware No Drawing. Filed Nov. 7, H60, Ser. No. 67,478 11 Claims. (Cl. 252138) The present invention relates to a detergent briquette which is resistant to abrasion and accidental breakage when dry and is also readily disintegrable in water. The invention includes a process for manufacturing such a briquette by moistening detergent particles, lightly com.- pacting the particles to a form-retaining briquette and applying to the surface of the briquette a coating of readily water soluble film-forming organic polymer.

In accordance with this invention a process for manufacturing a detergent briquette comprises mixing together a normally solid water soluble anionic organic detergent with a normally solid water soluble inorganic salt, producing therefrom a particulate detergent containing up to 21% moisture, applying 4 to 12% added water to the detergent particles to increase the moisture content thereof to 4 to 25%, pressing the detergent particles to a lightly compacted readily disintegrable solid briquette of desired shape at a pressure between 3 and 100 pounds per square inch and applying to the briquette a proportion between about 1 and 5% of a readily water soluble polyvinyl alcohol. This water soluble film-forming polymer forms a very satisfactory coating on the surface of the detergent briquette and, in the proportions mentioned the coating is of average thickness from about 0.05 to 0.8 millimeter. The polyvinyl alcohol which makes a very good coating is of a weight average degree of polymerization of about 30 to 300 and a polyvinyl acetate content of about to 30% The water soluble detergent briquette obtained in accordance with this invention is one that has been found to be commercially acceptable because of its improved resistance to abrasion and accidental breakage when dry, during packing, transportation and handling, and also because it disintegrates and dissolves quickly in water. This briquette comprises a multiplicity of solid particles of water soluble synthetic organic anionic detergent and water soluble inorganic salt, of specified moisture content, lightly compacted and fused together at moistened areas of contact, the briquette being coated with a thin adhering and binding film of water soluble polymer.

The organic detergent employed is a water soluble anionic material which is normally solid and is possessed of good detersive properties. Among such compounds are the sulfated and sulfonated synthetic detergents such as the alkyl aryl sulfonates, preferably alkyl benzene sulfonates of 12 to 20 carbon atoms in the alkyl group, e.g., propylene or other lower alkylene polymers of 12 to 15 carbon atoms; fatty alcohol sulfates, e.g., sulfates of higher fatty alcohols such as lauryl, myristic and palmityl obtained from coconut oil; higher fatty acid amides of N-methyl taurine; alpha-sulfonated higher fatty acids; normal higher fatty alkyl sulfonates; and other sulfuric reaction product detergents having higher fatty alkyl or acyl hydrophobic radicals. In this specification the term higher, when applied to alkyl and acyl groups, denotes a content of carbon atoms of 12 to 20. Lower, indicates 1 to 4 carbon atoms in such radicals. All the above detergents are usually employed in the forms of their water soluble salts, such as their alkali metal salts. Although sodium is the salt forming cation most prefer- 3,240,712 Patented Mar. 15, 1966 able, potassium and magnesium detergents may also find use, especially when employed as only a part of the total synthetic content of these briquettes.

Although detergent particles comprising synthetic anionic detergents may be made into briquette form in accordance with this invention, the most preferable and most useful anionic detergents at present are the alkyl benzene sulfonates previously described and these compounds, preferably in the form of the sodium salt of propylene tetramer benzene sulfonate, sodium salt of propylene pentarner benzene sulfonate and mixtures thereof, will most preferably constitute all or a substantial proportion, usually more than 50%, of the synthetic anionic organic detergent content of the briquetted composition.

The alkyl aryl sulfonate detergents are excellent and economical washing agents but, in the absence of builders, are often of a stickiness that sometimes will make it very difficult to produce from them readily disintegrable detergent briquettes which would still be form-retaining and easy to handle. The other non-soap synthetic organic detergents are also often softer, tackier and more diificult to process than the older anionic organic detergent materials such as the fatty acid soaps, although they are not usually as difficult to make into satisfactory briquettes as are the alkyl aryl sulfonates. By the addition of water soluble inorganic salt, usually alkali metal salt, to the synthetic organic detergent, the detergent particles can be hardened to a degree and made more suitable for formation into briquettes. Among the materials that are most often employed for this purpose are sodium tripolyphosphate, tetrasodium pyrophosphate, sodium sulfate, potassium sulfate, sodium chloride and other builders and fillers. Of the various salts that have been utilized, it is found that the water soluble polyphosphates such as the alkali metal salts are highly preferred. These compounds, especially sodium tripolyphosphate and tetrasodium pyrophosphate, substantially improve the detersive ability of the synthetic organic detergent and have physical and chemical properties which aid in the production of a satisfactory form-retaining, yet readily disiutegr-able detergent briquette. Instead of the sodium polyphosphates the potassium salts may be used, usually in mixture with those of sodium. Compounds which improve detergency, like the polyphosphates, are builders while those which primarily add bulk, like the sulfates and chlorides, are fillers.

The proportions of synthetic anionic organic detergent and inorganic builder salt may be varied within rather Wide ranges so long as the mixture obtained is of acceptable cohesion while still disintegrating rapidly in Water under washing conditions. Usually 20 to 40% and preferably 25 to 35% anionic detergent such as sodium alkyl benzene sulfonate of the type described and usually 20 to preferably 30 to 55% inorganic builder salt, such as 40% sodium tripolyphosphate, are employed. Various adjuvants such as perfume, pigment, dyes and other coloring agents, foaming agents, foam stabilizers, inorganic salt fillers, anti-redeposition agents, antibacterial compounds, sequestrants, antioxidants, corrosion inhibitors, anti-forms and other materials intended to improve one or more specific characteristics of the composition may also be added or included, usually in amount from about 1 to 30%.

The balance of the detergent briquette composition, with the exception of a coating material to be described later, is water, present to the extent of from 4 to 25%, usually 8 to 19% and preferably 13 to 19%. Within the preferred range, 15% moisture briquettes are usually most acceptable. Relatively high proportions of moisture, such as are present in the preferred briquettes, are unusual in solid detergent products of this general type but, in conjunction with a thin coating of water soluble film-forming polymer on the detergent briquette, have been found to be helpful in obtaining a product which is readily disintegrable in water.

A water soluble polymer found to be especially effective in maintaining a high degree of water solubility of the detergent briquettes and simultaneously increasing their strength and resistance to abrasion is polyvinyl alcohol. The polyvinyl alcohols of commerce usually contain minor proportions of a lower fatty acid ester, polyvinyl acetate. This may be present in polyvinyl alcohols employed in this invention to the extent of about to 30%. The useful polyvinyl alcohols are also of a weight degree of polymerization between about 30 and 300. Instead of the weight average degree of polymerization designation, such coatings may be characterized by viscosity measurements, which are related to the degree of polymerization and molecular weight of the polyvinyl alcohol. Thus, a 4% solution of a polyvinyl alcohol of the mentioned degree of polymerization and polyvinyl acetate content will have a viscosity of about 1.5 to 7 centipoises at Centigrade. A good polyvinyl alcohol for use in accordance with the invention has a weight average degree of polymerization of about 50 to 250 (viscosity of about 2 to 6 centipoises) and a polyvinyl acetate content of 15 to and a most preferred material has a weight average degree of polymerization of about 100 (viscosity of 3.5 centipoises) and polyvinyl acetate content of 20%. The polyvinyl acetate contents and average degree of polymerization given are meaningful measurements of suitability of the polyvinyl alcohol for use as a briquette surface treatment. Above a polymerization degree of about 300 or acetate content over the polyvinyl alcohol becomes difficult to dissolve quickly enough to permit rapid disintegration of the briquette. Below 10% acetate and below a polymerization degree of 30 the film made is not usually sufliciently protective of the briquette.

The polyvinyl alcohol used in this invention should be compatible with the detergent materials and various adjuvants that may be included with them. It should contain relatively little insoluble matter, should be colorless, odor-free and of neutral pH. Deviations from the above requirements may be made where warranted but, in general, the polyvinyl alcohol of the recited specifications would be most acceptable for household detergent products. Instead of the described polyvinyl alcohol, other readily Water soluble synthetic organic filmforming polymers of similar properties can be used, but usually such other compounds will not be as effective. However, polyvinylprollidone, sodium craboxymethyl cellulose, hydroxypropyl methyl cellulose and similar polymeric substances can produce water soluble films for briquette surfaces. When used, it is preferred to mix them with polyvinyl alcohol so that the special advantages attending the presence of that material may be retained.

In making detergent briquettes it is possible to mix together the anionic synthetic organic detergent, which is preferably sodium alkyl benzene sulfonate, together with the inorganic builder salts, such as sodium tripolyphosphate or other polyphosphates and then briquette the physical mixture of these powders. Often, the cohesion of the materials is not accurately controllable and, if of satisfactory disintegration characteristics in water the briquettes might also tend to break more readily when handled. A much more preferably way of producing these briquettes is by initially mixing the organic detergent and builder salt in an aqueous medium, such as a crutcher mix, in which a very uniform slurry of these components is produced, and then drying to desired form and moisture. The moisture content of the slurry should usually be from 30 to 50% and more often is about The slurry will generally contain all the anionic organic detergent and inorganic builder salt to be found in the final briquette, together with the various adjuvants used, except such as may be too unstable under the conditions of converting the slurry to a solid material. If desired, the materials of lesser stability, e.g., perfumes, may be added to the dried detergent prior to the application of moisture thereto and subsequent compacting.

The best way of converting the fluid mixture of briquette components to a most satisfactory form for compacting is by spraying the slurry through a small orifice or by otherwise atomizing it into a gas and passing it through a drying zone in which it is contacted and partially dehydrated by a heated drying gas. During the drying operation, detergent globules are formed which become what may be considered to be the substantially spherical particles obtained from spray drying processes. Due to the expansion of the detergent globules when heater, often these beads are hollow and of low density, thereby facilitating their ready dissolution in water. The temperature of the drying gas used is usually between 300 Fahrenheit and 600 Fahrenheit, depending upon the type of material being dried. The detergent beads obtained contain a substantially homogeneous mixture of organic detergent and builder salt. The builder may be somewhat changed by the drying operation, it being known that sodium tripolyphosphate is partially converted to other phosphate salts when heated, but usually drying conditions are controlled to minimize such alterations. The dried beads are usually of apparent bulk density between 0.3 and 0.5 grams per cubic centimeter, preferably 0.4 gram per cubic centimeter, such density being obtained by pouring a sample of beads into a cylindrical container of known volume and weighing the contents. Although the beads may be dried to a moisture content up to 21%, more often the drying is controlled so that 2 to 15% moisture is present in the beads when they are removed from the drying zone. Less than 2% initial moisture in the beads makes them more friable and also requires the addition of more moisture in a moistening operation before compacting. Such additional moisture may not be as readily absorbed as desired and can cause some adhesion of the detergent briquette to the pressing dies. Above 15% initial moisture, the detergent beads tend to become more adherent to other beads and equipment walls and become diflicult to transport and handle easily, especially when warm, as they are after spray drying. A preferred moisture content is 6 to 12% and for built alkyl benzene sulfonate detergents one usually finds that about 8% moisture is most desirable.

To facilitate production of a quickly dissolving briquette of desired density, the atomization of the slurry and the drying conditions should also be controlled to produce detergent particles which are approximately globular and have diameters which will allow them to pass through a No. 5 US. sieve and be retained on a No. 140 sieve, preferably passing through a No. 8 or No. 12 sieve With less than 10% passing a No. sieve. A small proportion of fines passing through the sieve may also be present Without exerting a very detrimental effect on the product but efforts should be made to keep the content of such particles to a practical minimum. Beads that pass the above sieve test specifications will be substantially within the range of 0.1 to 4 millimeters diameter, preferably 0.15 to 2.5 millimeters. These are ranges of diameters over which the particles are distributed, the distribution usually approximating the normal. However, various mixtures of particles within the ranges may also be used providing that extreme disparities are avoided.

Detergent beads of the composition of the final product, except for the presence of the polyvinyl alcohol coating material, are next sprayed with additional water before compacting to briquette form. If desired and found useful, the water may be the solvent portion of an aqueous medium containing dissolved or dispersed substances to regulate the spray properties or to be coated onto the particles or mixed therewith. However, usually it is preferred to employ only Water, without a solute. The sprayed water is in finely divided droplet form and is directed onto the detergent beads as they are mixed or tumbled, so as to obtain a very uniform distribution of 'water spray throughout the detergent. The amount of Water sprayed onto the beads is usually about 4 to 12%, preferably 4 to and most preferably, about 7% and will raise the moisture content thereof to the ranges of proportions previously given. It has been found that it is usually preferable to add more moisture to the spray dried beads of initially lower moisture content than to beads originally somewhat higher in water content. The final moisture content of beads of the former type should also be in the lower parts of the ranges given. Thus, one might add 10% of moisture to detergent beads containing only 2% initial moisture and obtain a product initially very much like one resulting from moistening a 10% moisture bead with 5% of added Water. However, for production efiiciency, ease of handling and more ready absorption of applied moisture it is usually most desirable to have the moisture content of the spray dried beads above 6% and preferably about 8%. During and after spraying the surfaces of the detergent beads with the required amount of moisture in finely atomized or fog form the beads are mixed well together to assure that the moisture is evenly distributed and may be absorbed evenly by the particles. It is preferred to continue mixing for about 1 to 30 minutes, most preferably about 3 minutes after spraying. The mixing should be by such a method that the particles are not substantially reduced in size. It has been found that tumbling allows maintenance of particle size within the ranges previously mentioned. If any particles form oversized agglomerates over 4 or 2.5 millimeters diameters they should be removed, preferably by screening. Although moistened detergent beads have been allowed to age before compacting, it is considered preferable to press these moistened particles into briquette form shortly after the application of additional moisture, usually within a couple of hours and preferably within about 30 minutes after moistening.

After the application of moisture the particles still are not objectionably adherent and can be readily conveyed to pressing means Where they are lightly compacted into desired shape at a pressure low enough to form a readily disintegrable briquette, between 3 and 100 pounds per square inch, preferably between and 50 pounds per square inch or to 40 pounds per square inch. At such pressures the pro-moistened detergent beads are converted to form-retaining briquettes which, when coated with polyvinyl alcohol, are sufficiently strong for commercial handling and still disintegrate rapidly in water in home laundry washing machines. Such briquettes have an apparent density of about 0.4 to 0.7 gram per cubic centimeter, preferably about 0.53 gram per cubic centimeter. The word briquette designates a solid made by compacting particles. It is notrestrictive of shape. In preferred briquettes the particles are not substantially changed in shape or size during compacting.

After pressing and before coating with polyvinyl alcohol or other suitable polymer a form-retaining briquette is obtainable which can dissolve quickly in Water and which still is of a surface strength and abrasion resistance that Will allow it to be shipped without excessive breakage. However, it has been found that even superior abrasion resistance is obtainable if the formed br-iquette is coated in accordance 'with this invention. In addition to the hydrating of the inorganic salts on the surface of the briquette, an aqueous solution of polyvinyl alcohol also forms a coating or film of that material around the briquette, giving it superior abrasion resistance and strength. The polyvinyl alcohol coating, although it is water soluble, does appear to decrease the solubility rate of the briquette. The present inventors found that the pre-moistening of the detergent materials before compacting enabled them to improve the solubility rate of coated briquettes and thereby allowed the production of a readily disintegrable product which still had increased surface strength and abrasion resistance. Such a discovery was important because the application of moisture before compacting would usually be considered to increase the cohesion of the particles, thereby making it even more difiicult for them to be readily separated and dissolved in Water. In addition to physically aiding the production of a strong briquette, the polyvinyl alcohol also improves the washing ability of the detergent composition by increasing the degree of dispersion of dirt and other soiling substances removed from the materials being Washed to prevent their redeposition upon those materials when the wash water is removed.

After the detergent briquette has been formed, it is coated with polyvinyl alcohol. This coating is preferably done by spraying onto the briquette surfaces a liquid comprising the polyvinyl alcohol. It is most preferred that the polyvinyl alcohol be dissolved in water and that the aqueous solution should be sprayed or atomized in fine droplet form as evenly as practicable onto the surface of the briquette. The spray solution may contain glycerol or other low polyols to serve as plasticizers to help to keep the polyvinyl alcohol flexible and resilient, detergents or wetting agents to improve wetting of the briquette and neutralizing agents, e.g., sodium bicarbonate, to improve the odor of the polyvinyl alcohol by reacting with free acid present. Among other plasticizers that may find use are glycols, e.g., ethylene glycol and sugar alcohols, such as sorbitol.

The amount of polyvinyl alcohol sprayed onto the briquette surface should be from 1 to 5% of the briquette Weight and it is desirable that the moisture added from the solvent for the polyvinyl alcohol should also be kept approximately within this range. A more preferred range of polyvinyl alcohol coating amounts is from 1.5 to 3% and about 1.9% of the coating is considered the best amount for general use. The polyvinyl alcohol is preferably applied as a 10 to 25% solution, such as a 17% solution in water, the proportion of such solutions used being from 9 to 18%, preferably about 11% of the briquette Weight. When sprayed onto the detergent briquette surface, the polyvinyl alcohol and its solvent fill the voids between particles and also cover the surfaces of the particles. Because the briquette before coating is not perfectly smooth, it is evident that the coating will be thicker in some spots than in others but it may be said that the average thickness is from 0.05 to 0.8 millimeter, preferably 0.08 to 0.5 millimeter, e.g., 0.2 millimeter. It has been noted that the dried film of polyvinyl alcohol, While it substantially covers the whole briquette, does sometimes contain minute thin spots or even perforations which might be of assistance in aiding the penetration of moisture into the briquette and speeding solution in water. Also sometimes air is entrained in the coating, increasing its thickness over the average thickness calculated from the weight of polymer applied and the area covered by it. Then too, the plasticizer, wetting agent, some moisture and other materials in the polymer spray tend to increase thickness and may promote solubility of the film.

After coating with polyvinyl alcohol solution, the briquette may be surface dried by forced air, heated air, infrared rays or other suitable drying means to remove essentially all the moisture accompanying the polyvinyl alcohol in the coating spray. Thus, the final product will be of about the same moisture content as that obtained in the particles before pressing. After drying, the briquette may be packed immediately in cartons ready for shipment and use. It is usually preferred that such cartons contain moisture barriers to assist in maintaining the correct moisture content in the briquette. Briquettes made in accordance with this invention may be shipped in commerce without breaking and even though stored for months before use will still disintegrate and dissolve rapidly when added to the tub of any of the conventional washing machines. They will also pass the rather severe strength and solubility requirements set for such products, withstanding a drop of at least 1 foot onto a hard surface, e.g., a metal plate, without breaking and also disintegrating in agitated water at 100 Fahrenheit in a washing machine within a period of one minute. The Washing machine referred to is a commercial top-loading machine with a center post agitator of average operating and design characteristics.

The following examples illustrate the invention. All percentages and proportions in the examples, this specification and the appended claims are by weight unless otherwise indicated.

Other adjuvants (anti-redeposition agents, fluorescent brightener, antioxidants) 1. 1 Water 35.7

The above crutcher formula was mixed to homogeneity at a temperature of about 165 Fahrenheit for about /2 hour. It was then sprayed into heated drying gas at a temperature of about 500 Fahrenheit and the sprayed fine droplets were partially dried as they passed through the heated gas. The spray dried detergent particles resulting were screened to pass through an 8 mesh sieve, hardly any particles being removed by the sieve, and it was found that less than 10% of the particles were small enough to pass through a No. 100 mesh sieve. The spray dried detergent had a bulk density of about 0.4 gram/cubic centimeter, a moisture content of 8.5% and a 1% solution in water was of pH 10. After cooling the detergent was treated with a fine spray of water while being agitated by tumbling. The spray was applied for a short period, less than 5 minutes, after which tumbling was continued for about to minutes. The agitation was such that the detergent particles were not broken and were substantially within the 8 to 100 mesh range of the said particles. Agglomerates greater than 10 mesh were removed by screening. The moisture content of the resulting product was 14%. About five minutes after cessation of tumbling the detergent beads were compacted to briquette shape.

At a pressure of 18 pounds per square inch the moistened detergent was pressed into briquettes which were approximately of cylindrical shape, 2 /2 inches in diameter and 1.31 inches thick and of density of .53 gram/ cubic centimeter. The upper and lower faces of the briquettes were beveled annularly and a diametric roove was formed across one face to facilitate division in half when so desired. The briquette weights averaged 53.9 grams.

Within an hour after briquetting the resulting tablets were sprayed with a solution of polyvinyl alcohol. This solution comprised 17% of a polyvinyl alcohol having a weight degree of polymerization of about 100 and a polyvinyl acetate content of about 20', 1% sodium bicarbonate, glycerine, 1.4% alkyl aryl sulfonate and the balance moisture. The polyvinyl alcohol solution was heated to a temperature of 150 Fahrenheit and was sprayed onto the briquette in two applications, one for each face of the tablet, resulting in the application of 1.9% polyvinyl alcohol and an average film thickness of about 0.4 millimeter, although it was apparent that the film was not perfectly even, containing as it did, many thin spots or perforations. The aqueous solvent in the coating solution was evaporated by infrared heating. The briquettes resulting had a moisture content of about 14%. They passed tests for resistance to breakage and abrasion, being dropped from a height of one foot onto a hard surface without showing any damage. Tablets dropped from a height of about 5 feet did exhibit slight cracking. As to disintegration times, when placed in a washing machine of the top loading agitator type (5 gallon capacity) the briquettes disintegrated in 20 to 30 seconds. At this time there could not be observed any detergent briquette fragments, although it must be realized that not all of the detergent particles had completely dissolved. Wash tests run on briquettes containing surface coatings of polyvinyl alcohol of this type showed that they washed clothes whiter than the detergent from which the briquettes had been made.

Example II From a crutcher mix of about 40% moisture content detergent beads of the following formula were made by spray drying by a method substantially like that of Example I.

Percent Sodium alkyl benzene sulfonate (the alkyl radical being a propylene polymer of 12 to 15 carbon The spray dried particulate detergent was substantially of spherical form, having a bulk density of about 0.4 and particle sizes ranging from 2.5 millimeters to 0.15 millimeter diameter, only about 5% thereof passing a No. U.S. sieve. Water was sprayed on the tumbling particles to raise the moisture content to 19%. After spraying, tumbling was continued for 5 to 10 minutes. Subsequently, the pre-moistened particles were lightly compacted at a pressure of about 15 to 20 pounds per square inch to a 40 gram tablet, 2% inches in diameter by 1 inch thick, of apparent density of 0.6 gram/ cubic centimeter.

The briquette made was coated with 0.75 gram of polyvinyl alcohol of weight average degree of polymerization of between 50 and 250 and polyvinyl acetate content of 15 to 25%. The average coating thickness was about 0.2 millimeter after air drying. The polyvinyl alcohol was applied as an aqueous spray containing about 17% polyvinyl alcohol, 1% sodium bicarbonate, 1.5% wetting agent and 2.5% glycerine.

The briquettes made were sufiiciently strong to withstand the drop test previously described, did not crumble and were not abraded severely during ordinary handling and disintegrated rapidly in use in commercial washing machines. Disintegration times of 20 to 33 seconds were obtained and re-checks made after storage for several months proved that distintegration times were still satisfactory.

Example III Percent Sodium higher alkyl benzene sulfonate (branched alkyl group of about 13 carbon atoms) 35 Sodium tripolyphosphate 38 Sodium silicate (principally orthosilicate) 7 Sodium sulfate 9 Other adjuvants 2 Moisture 9 Detergent beads of the above formula were made by spray drying as described in the other examples. The beads were of particle sizes substantially between the sizes of the Nos. 8 and 100 US. sieves and were of densities from 0.3 to 0.4 gram/cubic centimeter. A series of briquettes was made using different proportions of added moisture and various compacting pressures, resulting in products of different densities. It was established by such experiments that 4 to 10% added moisture and compacting at pressures of about to 50, preferably to 40 pounds/square inch, will result in coated briquettes (coated with about 2% of polyvinyl alcohol) which will disintegrate in agitated wash water within a minute and which will still be of sufiicient strength, when dry, to withstand the drop test and will not be easily abraded during handling.

Thus, this detergent, at a density of 0.34 gram/cubic centimeter, moistened with 5.6% water applied as a fine spray while the detergent was agitated, pressed at pounds/square inch to a density of 0.53 produces a briquette which will disintegrate in water within 25 seconds. When coated with 2% polyvinyl alcohol of the type described, this briquette will still disintegrate satisfactorily and will be strong enough for commercial handling and shipment. Similarly, the addition of 9.1% moisture to beads of 0.33 gram/cubic centimeter and pressing at 18 pounds/square inch to a briquette of 0.53 gram/cubic centimeter or addition of 7.2% moisture to beads of 0.34 gram/cubic centimeter and pressing at 38 pounds/square inch to a density of 0.57 gram/ cubic centimeter result in excellent quickly disintegrating strong briquettes, when subsequently coated with polyvinyl alcohol.

In contrast to the results of these experiments it was found that compressing beads of 9.2% moisture content and density of 0.37 gram/cubic centimeter at a pressure of 38 pounds/square inch to a density of even as little as 0.45 gram/cubic centimeter yielded a briquette that failed to disintegrate satisfactorily, even the uncoated briquettes of this type taking about 4 minutes to disintegrate in a washing machine.

The present invention has been illustrated by description of the invented products made and manufacturing methods employed. These examples are illustrative only and are not to be considered as limiting the allowed claims.

What is claimed is:

1. A process for manufacturing a detergent briquette comprising mixing together 20 to percent of a normally solid water soluble anionic organic detergent selected from the group consisting of sulfated and sulfonated synthetic detergents with 20 to 70 percent of a normally solid water soluble inorganic hydratable builder salt, producing therefrom a particulate detergent containing 2 to 21% moisture, applying 4 to 12% added water to the detergent particles to increase the moisture content thereof to 6 to 25% and to improve the disintegrability of the briquette later formed, said application of the predetermined proportion of water being effected while the particles are tumbled thereby effecting a uniform distribution of the added water over the surfaces of the detergent particles, pressing the detergent particles into a lightly compacted solid briquette at a pressure of between 3 and 100 pounds per square inch to form a readily disintegrable briquette and applying to the briquette a proportion between 1 and 5% of a readily water soluble synthetic organic film-forming polymer selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, sodium carboxymethylcellulose and hydroxypropyl methyl cellulose to form on the briquette surface a water soluble film which is of strength suflicient to help make the detergent briquette resistant to abrasion and accidental breakage, when dry, and of such ready solubility that the detergent briquette will be readily disintegrable in water.

2. A process for manufacturing a detergent briquette resistant to abrasion and accidental breakage, when dry, and readily disintegrable in water, comprising mixing together 20 to 40 percent of a normally solid water soluble anionic organic detergent selected from the group consisting of sulfated and sulfonated synthetic detergents with 20 to 70 percent of a normally solid water soluble inorganic hydratable builder salt, producing therefrom a particulate detergent containing 2 to 21% moisture, applying 4 to 12% added water to the detergent particles to increase the moisture content thereof to 6 to 25% and to improve the disintegrability of the briquette later formed, said application of the predetermined proportion of water being efiected while the particles are tumbled thereby effecting a uniform distribution of the added water over the surfaces of the detergent particles, pressing the detergent particles to a lightly compacted readily disintegrable solid briquette of desired shape at a pressure between 3 and pounds per square inch and applying to the briquette a proportion between about 1 and 5% of a readily water soluble polyvinyl alcohol of a weight average degree of polymerization of about 30 to 300 and a polyvinyl acetate content of about 10 to 30% to form on the surface of the detergent briquette a water soluble coating of an average thickness from about 0.05 to 0.8 millimeter.

3. A process for manufacturing a detergent briquette resistant to abrasion and accidental breakage, when dry and readily disintegrable in water comprising mixing together in an aqueous medium 20 to 40 percent of a normally solid water soluble non-soap synthetic anionic organic detergent selected from the group consisting of sulfated and sulfonated synthetic detergents with 20 to 70 percent of a normally solid water soluble inorganic hydratable builder salt, atomizing the aqueous mixture of said materials into a gas, producing a particulate detergent containing 2 to 21% moisture, applying 4 to 12% added water to the detergent particles in finely divided droplet form to increase the moisture content thereof to 6 to 25 and to improve the disintegrability of the briquette later formed, said application of the predetermined proportion of water being effected while the particles are tumbled thereby effecting a uniform distribution of the added water over the surfaces of the detergent particles, mixing the moistened particles together, pressing the particles to a lightly compacted readily disintegrable solid briquette of desired shape at a pressure between 3 and 100 pounds per square inch and applying to the briquette a proportion between about 1 and 5 of a readily water soluble polyvinyl alcohol of a weight average degree of polymerization of about 30 to 300 and a polyvinyl acetate content of about 10 to 30% to form on the surface of substantially the whole detergent briquette a water soluble coating of an average thickness from about 0.05 to 0.8 millimeter.

4. A process for manufacturing a detergent briquette resistant to abrasion and accidental breakage, when dry, and readily disintegrable in water comprising mixing together, in an aqueous medium, a slurry of 20 to 40 percent of a normally solid water soluble alkyl aryl sulfonate detergent in which the alkyl group is of 12 to 20 carbon atoms with 20 to 70 percent of a normally solid water soluble inorganic polyphosphate builder salt, atomizing the slurried material into a drying gas, partially drying said material to a particulate detergent containing 2 to 15% moisture, applying 4 to 12% added water to the detergent particles in finely divided droplet form while agitating and mixing the particles, the amount of water added being sufficient to raise the moisture content of the particles to 8 to 19% and to improve the disintegrability of the briquette later formed, said agitating and mixing being by tumbling in a rotary drum, thereby effecting a uniform distribution of the added water over the surfaces of the detergent particles, pressing the particles to a lightly compacted readily disintegrable solid briquette of desired shape at a pressure between 15 and 50 pounds per square inch and applying to the briquette 1.5 to 3% of a readily Water soluble polyvinyl alcohol of a weight average degree of polymerization of about 30 to 300 and a polyvinyl acetate content of about to 30% to form on the surface of substantially the whole detergent briquette a water soluble coating of average thickness from about 0.08 to 0.5 millimeter.

5. A process for manufacturing a detergent briquette resistant to abrasion and accidental breakage, when dry, and readily disintegrable in Water comprising mixing together, in an aqueous medium, a 20 to 40 percent slurry of sodium alkyl aryl sulfonate detergent in which the alkyl group is of 12 to 20 carbon atoms with a 20 to 70 percent of a normally solid inorganic polyphosphate builder salt, atomizing the slurried material into a heated drying gas, partially drying said material to a particulate detergent substantially of spherical bead shape of diameters within the range of 0.1 to 4 millimeters containing 2 to moisture and of apparent density between 0.3 and 0.5 grams per cubic centimeter, removing the detergent beads from the drying gas, applying 4 to 10% Water to the detergent beads as a spray, while mixing them together, the mixing being by tumbling the beads so that the moisture is uniformly distributed over the surfaces thereof while the beads are maintained intact and substantially within the 0.1 to 4 millimeters diameter range, the addition of water being suflicient to increase the moisture content of the beads to 8 to 19% and to improve the disintegrability of the briquette later formed, removing agglomerated particles over 4 millimeters diameter, pressing the particles to a lightly compacted readily disintegrable solid briquette of desired shape of apparent density of 0.4 to 0.7 gram per cubic centimeter at a pressure between 15 and 50 pounds per square inch and applying to the briquette, in an aqueous medium, 1.5 to 3% of a readily water soluble polyvinyl alcohol of a weight average degree of polymerization of about 30 to 300 and a polyvinyl acetate content of about 10 to 30% to form on the surface of substantially the whole detergent briquette a water soluble coating of average thickness from about 0.08 to 0.5 millimeter.

6. A process for manufacturing a detergent briquette resistant to abrasion and accidental breakage, when dry, and readily disintegrable in water comprising mixing together, in an aqueous medium, a slurry of sodium alkyl benzene sulfonate detergent in which the alkyl group is a poly lower alkylene of 12 to carbon atoms with a normally solid water soluble inorganic polyphosphate builder salt selected from the group consisting of sodium tripolyphosphate and tetrasodium pyrophosphate, the moisture content of the slurry being from to 50%, atomizing the slurried material into a heated drying gas, partially drying said material to a particulate detergent substantially of spherical bead shape of diameters within the range of 0.15 to 2.5 millimeters and containing 20 to sodium alkyl benzene sulfonate, 20 to 70% inorganic builder salt 6 to 12% moisture, of apparent density between 0.3 and 0.5 gram per cubic centimeter, removing the detergent beads from the drying gas, applying 4 to 10% water to the detergent beads as a spray, while tumbling the beads to uniformly distribute the added moisture over the surfaces thereof while maintaining the beads intact and substantially within the 0.15 to 2.5 millimeters diameters range, the addition of water being sufiicient to increase the moisture content of the beads to 13 to 19% and to improve the disintegrability of the briquette later formed, removing agglomerated particles over 2.5 millimeters diameter, pressing the particles, within 2 hours after moistening, to a lightly compacted readily disintegrable solid briquette of desired shape of apparent density of 0.4 to 0.7 gram per cubic centimeter at a pressure between 15 and 50 pounds per square inch and applying to the briquette surface 1.5 to 3% of a readily water soluble polyvinyl alcohol of a weight average degree of polymerization of about 50 to 250 and a polyvinyl acetate content of about 15 to 25% by applying to the briquette 9 to 18% of an aqueous solution containing 10 to 25% of such polyvinyl alcohol and drying the applied polyvinyl alcohol solution to form on the surface of substantially the whole detergent briquette a water soluble coating of average thickness from about 0.08 to 0.5 millimeter.

7. A process for manufacturing a detergent briquette resistant to abrasion and accidental breakage, when dry, and readily disintegrable in water comprising mixing to gether, in an aqueous medium, a slurry of sodium alkyl benzene sulfonate detergent in which the alkyl group is a polypropylene of 12 to 15 carbon atoms with sodium tripolyphosphate, the moisture content of the slurry being about 40%, atomizing the slurried material into a heated drying gas, partially drying said material to a particulate detergent substantially of diameters distributed 'over the range of 0.15 to 2.5 millimeters and containing 25 to 35% sodium alkyl benzene sulfonate, about 40% phosphate salt from the sodium tripolyphosphate content of the slurry, about 8% moisture, of apparent density about 0.4 gram per cubic centimeter, removing the detergent beads from the drying gas, applying about 7% water to the detergent beads as a spray while tumbling the beads to uniformly distribute the added moisture over the surfaces thereof while maintaining the beads intact and substantially within the 0.15 to 2.5 millimeters diameters range, and to improve the distintegrability of the briquette later formed continuing mixing together of the moistened particles for a period of about 3 minutes after application of moisture thereto, screening out agglomerated particles over 2.5 millimeters diameter, pressing the particles, within 2 hours after moistening, to a lightly compacted readily disintegrable solid briquette of desired shape of apparent density of about 0.53 gram per cubic centimeter at a pressure of about 20 to 40 pounds per square inch and applying to the briquette surface about 11% of the briquette weight of an aqueous solution containing about 17% readily water soluble polyvinyl alcohol of a weight average degree of polymerization of about and a polyvinyl acetate content of about 20% to form a thin coating of polyvinyl alcohol over the surface of substantially the Whole briquette which is about 1.9% of the briquette weight and drying the aqueous solution so that the briquette is maintained at a moisture content of about 15 th average thickness of the water soluble polyvinyl alcohol coating produced being about 0.2 millimeter.

8. A water soluble detergent briquette which is resistant to abrasion and accidental breakage, when dry, and disintegrates readily in water, comprising a multiplicity of solid particles of 20 to 40 percent of a soluble anionic organic detergent selected from the group Consisting of sulfated and sulfonated synthetic detergents and 20 to 70 percent of a water soluble inorganic hydratable builder salt, of 6 to 25 moisture content, in the form of adhering particles initially of a moisture content of 2 to 21%, to the surfaces of which 4 to 12% water was added to improve disintegrability of the briquette, lightly compacted and fused together at the moistened areas of contact by a low pressure to form a shaped briquette, said particles containing a uniform distribution of the added Water over the surfaces thereof, coated with an adhering and binding film of 1 to 5% readily water soluble synthetic organic film-formng polymer selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, sodium carboxymethylcellulose and hydroxypropyl methylcellulose of strength sufl'icient to help make the detergent briquette resistant to abrasion and accidental breakage, when dry, and of such ready solubility that the detergent briquette disintegrates readily in Water.

9. A water soluble detergent briquette which is resistant to abrasion and accidental breakage, when dry, and disintegrates readily in water, comprising a multi plicity of solid particles composed of a homogeneous mixture of 20 to 70 percent of a water soluble anionic organic detergent selected from the group consisting of sulfated and sulfonated synthetic detergents and 20 to 40 percent of a water soluble inorganic hydratable builder salt, of 6 to 25% moisture content, in the form of adhering particles initially of moisture content 2 to 21%, to the surfaces of which 4 to 12% water was added to improve disintegrability of the briquette, lightly compacted and fused together at the moistened areas of contact by application of a pressure between 3 and 100 pounds per square inch to form a shaped briquette said particles containing a uniform distribution of the added water over the surfaces thereof, coated with an adhering and binding film of 1 to 5% of a readily water soluble polyvinyl alcohol of a weight average degree of polymerization of about 30 to 300 and a polyvinyl acetate content of about to 30% which forms on the surface of the detergent briquette a water soluble coating of an average thickness from about 0.05 to 0.8 millimeter.

10. A water soluble detergent briquette which is resistant to abrasion and accidental breakage, when dry, and disintegrates and dissolves readily in water, comprising a multiplicity of solid particles composed of a homogeneous mixture of 20 to 40 percent of a water soluble alkyl aryl sulfonate detergent in which the alkyl group is of 12 to 20 carbon atoms, and 20 to 70 percent of a water soluble inorganic polyphosphate builder salt, of 8 to 19% moisture content, in the form of adhering particles initially of a moisture content of 2 to and apparent density between 0.3 and 0.5 gram per cubic centimeter, to which 4 to 10% water was added to improve disintegrability of the briquette, lightly compacted and fused together at the moistened areas of contact by application of a pressure between 15 and 50 pounds per square inch to form a shaped briquette of apparent density of 0.4 to 0.7 gram per cubic centimeter, said particles containing a uniform distribution of the added water over the surfaces thereof, coated with an adhering and binding film of about 1.5 to 3% of a readily water soluble polyvinyl alcohol of a weight average degree of polymerization of about 30 to 300 and a polyvinyl acetate content of about 10 to 30%, which forms on the surface of substantially the whole detergent briquette a water soluble coating of average thickness from about 0.08 -to 0.5 millimeter, said briquette disintegrating in agitated water at 100 F. in less than 1 minute and being resistant to abrasion and capable of withstanding a drop of 1 foot onto a hard surface, without breaking.

11. A water soluble detergent briquette which is resistant to abrasion and accidental breakage, when dry, and disintegrates and dissolves readily in water, comprising a multiplicity of spray dried solid particles of diameters substantially within the range of 0.15 millimeter to 2.5 millimeters, composed of a homegeneous mixture of 20 to 40 percent of a sodium alkyl benzene sulfonate detergent in which the alkyl group is of 12 to 20 carbon atoms and 20 to percent of a water soluble inorganic sodium polyphosphate builder salt, of 13 to 19% moisture content, in the form of adhering particles initially of a moisture content of 6 to 12% and apparent density between 0.3 and 0.5 gram per cubic centimeter to which 4 to 10% water was added to improve disintegrability of the briquette, lightly compacted and fused together at the moistened areas of contact by application of a pressure between 15 to 50 pounds per square inch to form a shaped briquette of apparent density of 0.4 to 0.7 gram per cubic centimeter said particles containing a uniform distribution of the added water over the surfaces thereof, coated With an adhering and strengthening binding film of 1.5 to 3% of a readily soluble polyvinyl alcohol of a weight average degree of polymerization of about and a polyvinyl acetate content of 15 to 25%, which forms on the surface of substantially the whole detergent briquette a water soluble coating of uneven thickness averaging about 0.08 to 0.5 millimeter, said briquette disintegrating in agitated water at 100 F. in less than 1 minute and being resistant to abrasion and capable of withstanding a drop of 1 foot onto a hard surface, without breaking.

References Cited by the Examiner UNITED STATES PATENTS 2,480,579 8/1949 Holuba 252--138 2,635,400 4/1953 Abbott et al 25293 XR 2,709,686 5/1955 Lewis et a1 252--138 XR 2,875,155 2/1959 Miles 252-138 OTHER REFERENCES Elvanol (Polyvinyl Alcohols), E. I. du Pont de Nemours & Co. (Inc.) Wilmington, Delaware (1947), (2nd printing, pages 13 and 17.

JULIUS GREENWALD, Primary Examiner. 

1. A PROCESS FOR MANUFACTURING A DETERGENT BRIQUETTE COMPRISING MIXING TOGETHER 20 TO 40 PERCENT OF A NOR MALLY SOLID WATER SOLUBLE ANIONIC ORGANIC DETERGENT SELECTED FROM THE GROUP CONSISTING OF SULFATED AND SULFONATED SYNTHETIC DETERGENTS WITH 20 TO 70 PERCENT OF A NORMALLY SOLID WATER SOLUBLE INORGANIC HYDRATABLE BUILDER SALT, PRODUCING THEREFROM A PARTICULATE DETERGENT CONTAINING 2 TO 21% MOISTURE, APPLYING 4 TO 12% ADDED WATER TO THE DETERGENT PARTICLES TO INCREASE THE MOISTURE CONTENT THEREOF TO 6 TO 25% AND TO IMPROVE THE DISINTEGRABILITY OF THE BRIQUETTE LATER FORMED, SAID APPLICATION OF THE PREDETERMINED PROPORTION OF WATER BEING EFFECTED WHILE THE PARTICLES ARE TUMBLED THEREBY EFFECTING A UNIFORM DISTRIBUTION OF THE ADDED WATER OVER THE SURFACES OF THE DETERGENT PARTICLES, PRESSING THE DETERGENT PARTICLES INTO A LIGHTLY COMPACTED SOLID BRIQUETTE AT A PRESSURE OF BETWEEN 3 AND 100 POUNDS PER SQUARE INCH TO FORM A READILY DISINTEGRABLE BRIQUETTE AND APPLYING TO THE BRIQUETTE A PROPORTION BETWEEN 1 AND 5% OF A READILY WATER SOLUBLE SYNTHETIC ORGANIC FILM-FORMING POLYMER SELECTED FROM THE GROUP CONSISTING OF POLYVINYL ALCOHOL, POLYVINYLPYRROLIDONE, SODIUM CARBOXYMETHYLCELLULOSE AND HYDROXYPROPYL METHYL CELLULOSE TO FORM ON THE BRIQUETTE SURFACE A WATER SOLUBLE FIM WHICH IS OF STRENGTH SUFFICIENT TO HELP MAKE THE DEGERGENT BRIQUETTE RESISTANT TO ABRASION AND ACCIDENTAL BREAKAGE, WHEN DRY, AND OF SUCH READY SOULBILITY THAT THE DETERGENT BRIQUETTE WILL BE READILY DISINTEGRABLE IN WATER. 